The present invention relates to a connector device for use in an internal combustion engine.
An internal combustion engine has been known in which the amount of fuel injected from the fuel injector is controlled on the basis of the output signal of an oxygen concentration detector arranged in the exhaust passage of the engine. In such an engine, the correction value of the basis fuel injection time period is normally calculated from the output signal of the oxygen concentration detector, and the actual fuel injection time period, which is necessary to equalize an air-fuel ratio to the stoichiometric air-fuel ratio, is determined by multiplying the basis fuel injection time period by the correction value. The mean value of the correction value is equal to, for example, 1.0, and the correction value is gradually increased when the oxygen concentration detector produces a leam signal, but the correction value is gradually reduced when the oxygen concentration detector produces a rich signal. When the feedback control of the fuel injection time period is started, a reference value such as 1.0 is put into the correction value, and then, the correction value is increased or reduced from the reference value.
However, if the engine is used for a long time, for example, the metering accuracy of the air flow meter for metering the amount of air fed into the cylinder of the engine deteriorates, and as a result, the output voltage of the air flow meter is offset from the regular output voltage indicating the actual amount of air. At this time, if the output voltage of the air flow meter is offset so that it indicates, for example, the amount of air, which is larger than the actual amount of air, since the basis fuel injection time period calculated from the engine speed and the output signal of the air flow meter becomes longer than a fuel injection time period which is necessary to equalize an air-fuel ratio to the stoichiometric air-fuel ratio, the mean value of the correction value becomes small. However, even if the mean value of the correction value becomes small as mentioned above, or becomes large by any other reason, when the feedback control of the fuel injection time period is started, the correction value is increased or reduced from, for example, 1.0. As a result of this, a problem occurs in that the air-fuel mixture becomes excessively lean or rich immediately after the feedback control is started.
In order to eliminate such a problem, a conventional engine is provided with an electronic control unit containing a back-up RAM therein. In this engine, the mean value of the correction value calculated over a long time is stored in the back-up RAM, and when the feedback control is started, the correction value is increased or reduced from the mean value of the correction value, which is stored in the back-up RAM.
However, in the case where, for example, the air flow meter is exchanged for a new one, the new air flow meter is adjusted so that the mean value of the correction value becomes equal to, for example, 1.0. Therefore, at this time, it is necessary to return again the mean value of the correction value, stored in the back-up RAM, to 1.0. However, in order to change data stored in the back-up RAM as mentioned above, it is necessary to detach the power supply terminal of the back-up RAM from the battery. Consequently, problems occur in that a tool for detaching the power supply terminal of the back-up RAM from the battery is necessary, and it takes a long time for detaching the power supply terminal of the back-up RAM from the battery. In addition, another problem occurs in that, when the power supply to terminal of the back-up RAM is connected again to the battery, it is not completely connected to the battery.